Using this ultrasensitive method, we observed that PrPSc from VPSPr and fCJDV180I was amplified very efficiently using the brain homogenate substrates from TgVV, non-CJD patients with PrP-129MM, and mixed brain homogenates with Tg180 and TgMM as well as less efficiently using TgMM and non-CJD patients with PrP-129VV. This evidence concerns the gene PRNP and Creutzfeldt Jacob disease.